PORTLAND, Ore. -- Researchers at the Oregon Health & Science University Cancer Institute have pinpointed the protein that can lead to genetic changes that cause lung cancer.

The researchers discovered that the production of the protein FANCD2 is slowed when lung cells are exposed to cigarette smoke. Low levels of FANCD2 leads to DNA damage, triggering cancer, senior author Grover Bagby said.

The study, published in the British Journal of Cancer, said cigarette smoke curbs the production of 'caretaker' proteins, like FANCD2, which normally prevent cancer by fixing damages in DNA and causing faulty cells to commit suicide.

FANCD2 is part of a family of proteins involved in an inherited condition called Fanconi anemia. People with the condition are more likely to develop cancers at a young age and have low levels of these proteins.

Lung cancer is the most common cancer in the world, with 1.3 million people diagnosed every year.